A fishing term used to classify an elite angler who always seems to be in the right place at the right time because he is always "on the fish". His prowess is so keyed in that you could put a sharpie in the worst possible fishing environment (weeds, snow, hurricane winds...), and he will still catch a trophy fish because he knows something that no one else knows, exactly how to present which lure/bait in which conditions to attract any fish that are present.

I was at the beach yesterday and there were 20 other guys and no one could catch a cold...except Adam, he's a real sharpie on the surf, I think they started called him the fish whisperer after his 7th bass

A type of permanent markers.
This brand name, "Sharpie" is used to talk about any type of permanent marker, like how we call all band-aids "Band-Aids", by the brand name, regardless of the actual name of the product.

"Hey, could someone pass me a Sharpie so I can finish my science poster?"

The sort of thing you look up, when you are sitting at your desk, and see an actual sharpie, and are so bored that you decide to look it up, to see what other losers wrote about it, because if you dont know the definition anyways you are a dumbf***k